The cylinders of the 1 1/2, 1st and 2nd Models are not interchangeable. Yes, they will fit, revolve and lock in battery but the cylinder charge holes will not align with the barrel and hammer. The 5-shot cylinder of the 1st Model has the cylinder stop (bolt) on the bottom frame whereas, the 2nd Model has the stop on the top. The Transition cylinder (non-fluted) has a cylinder unique to the Transition in that the 2nd model frame used on this revolver has the cylinder stop on the top. The Transition cylinder has the cylinder stop notches cut around its perimeter like the fluted cylinder of the 2nd Model.